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IconArchive - more than half a million icon sets. ...

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Icondeposit - free icons from Android & iOS apps.

Justinmind. If you're an avid Justinmind user and are looking for the perfect set of free app icons for Android or iOS app prototypes, we'd recommend heading over to our UI kits page. ...

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Iconfinder. ...

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Sketch App Sources. ...

Material Design.